This invention relates to a screen printer, and more particularly to a screen printer of the type in which only that portion supporting a squeegee is angularly turned up and down so as to facilitate the exchange of the squeegee.
In a screen printer, a screen or plate (i.e., printing pattern-bearing sheet) having a printing pattern is superposed on an object to be printed, and printing ink is coated onto the screen by the use of a squeegee, thereby effecting a printing. The squeegee is attached to a squeegee head through a support member. The squeegee head is supported by two parallel guide rails, and is movable by means of the combination of slide guides and the guide rails of a circular cross-section respectively receiving them. Conventional screen printers of such a construction are disclosed, for example, in Japanese Patent Unexamined Publication No. 62-84588 and Japanese Utility Model Unexamined Publication No. 62-154834.
However, recently, in the type of screen printer for printing a pattern, such as an electronic circuit, on a board, commercially-available guides of the linear motion-type employing ball bearings are used as guides for the squeegee head. Such guide of the linear motion-type is excellent in precision and smoothness of the guiding. Further, recently, instead of a pneumatic cylinder, a combination of an electric motor and a ball screw is used as a drive device for reciprocally moving the squeegee head, and this combination is excellent in smoothness of the movement and speed control.
In conventional screen printers, a guide mechanism, including guide rails, and the squeegee head are both supported on a frame. The whole of this frame is pivotally movable or movable upward and downward to provide a space below the squeegee for the purpose of exchanging the squeegee.